The story begins with Edward Snowden’s initial efforts to find a newspaper reporter who would accept his cache of NSA documents. But the program is not about Snowden. At most he’s the subject for less than 10 minutes. The story is about “The Program,” the still unfurling domestic information collection effort that began after September 11, 2001 and — apparently — continues. It’s about patriotism, ethics, heroism, personal tragedy, tough choices, lying, prosecution, persecution, and using the Constitution as a dependent variable.

While the program has a point of view, the main characters in a tale as narratively engaging as All The President’s Men do get their say. You can watch extended interviews of the main characters — The Whistleblowers (Snowden is not one of them), the Government Officials (including Andrew Card, Michael Hayden, and Alberto Gonzales), and the journalists (including Glen Greenwald) — at this link: http://www.pbs.org/wgbh/pages/frontline/oral-history/united-states-of-secrets/.

On May 20, FRONTLINE continues the story of mass surveillance in America in part two of United States of Secrets, an investigation into the secret relationship between Silicon Valley and the National Security Agency.

Companies like Google and Facebook gather massive amounts of data on its users around the world, which they use to sell and create advertisements. To the U.S. government, it is a treasure-trove of information that regularly reveals what we do, who we know and where we go.

The revelations by former NSA contractor Edward Snowden helped to uncover the role the tech industry played — at times unwittingly, but often with consent — in the NSA’s massive dragnet.

So how did the tech giants react when the government asked them to turn over data on millions of ordinary American citizens? And how much do companies like Google, Facebook and Yahoo really know about you?

Find out on May 20 starting at 10 p.m. EST on most PBS stations. (Check local listings.)

I hope one can ignore the marketing hyperbole. Tuesday’s program was unsettling.